1. Field of the Invention
The present invention relates to a measuring method useful when a predetermined quantity of particulate material such as chip devices, powder, or the like is measured to be removed and, moreover, the present invention relates to a measuring apparatus.
2. Description of the Related Art
To measure material which is being conveyed, with high accuracy in a short measuring-time, it is rational that the conveying rate of the material is high until the quantity of the measured material reaches a final measuring target value, and the conveying rate is low when the quantity of the measured material reaches the final measuring target value. Specifically, as a means for carrying out the above-described measurement, it is proposed that the conveying speed of a conveying unit at which material to be measured is conveyed is controlled so that conveying of the material at a large conveying rate and that at a very small conveying rate are changed from one to the other. In addition, it is supposed that a device for conveying material at a large conveying rate and a device for conveying the material at a very small conveying rate are equipped, and moreover, means for selecting these devices is provided. Japanese Unexamined Patent Application Publication No. 7-311077 (Patent Document 1) discloses means for carrying out the above-described measurement using the selection of the devices.
Referring to controlling the conveying-speed of the conveying unit so that the conveying rates are changed as described above, it is advantageous that only one type of conveying unit is required. However, it is difficult to uniformly convey material at a very small conveying rate by means of the conveyor. Furthermore, to decrease the conveying rate to the very small conveying rate, the conveying speed must be decreased. Thus, it takes much time for a required quantity of the material to be measured for removal. Thus, as a whole, it takes much time to carry out the overall measuring process. As a result, the efficiency of the entire process is greatly reduced.
According to the known means disclosed in Patent Document 1, parts can be measured to be removed with high accuracy, compared to the measurement of parts in which the weight of parts fed through a single hopper is measured, and a predetermined quantity of the parts are removed. However, according to this known means, the apparatus is large in size and also, is voluminous as a whole, so that the space required for the installation of the apparatus is large. Moreover, the apparatus is expensive. Therefore, the above-described means is unsuitable for measurement of a predetermined relatively small quantity of material which is to be removed.